1. Field of the Invention:
The present invention relates to improvements in a cutting head for a cord type mower having a rotary casing which contains a spool storing cords which are fed out as the tip portions of the cords are worn, and rotates at a high speed to cut or sever grass or weeds and, more particularly, to improvements in the construction of a cutting head for a cord type mower, for simplifying winding new cords on the spool and for automatically and properly regulating feeding out the cords as the tip portions of the cords are worn or broken off during the mowing operation.
2. Description of the Prior Art:
Various techniques for such purposes have been proposed and applied to practical cutting heads for cord type mowers.
In a conventional cord type mower, for example, a cover attached to the lower end of a rotary casing is struck to remove same from the rotary casing, and then a cord spool is rotated relative to the rotary casing to unwind the cords wound on the spool.
Japanese Unexamined Patent Publication (Kokai) No. 60-83508 discloses a cord type mower having a plurality of interlocking projection means formed on the lower surface of a cord spool contained in a rotary casing which is rotated by a driving source and on a bottom plate attached to the bottom of the rotary casing so as to engage when the cord spool is pressed down by springs, a centrifugal clutch for the cord spool, comprising a plurality of radial ball guide grooves formed in the lower surface of the central pressure plate of the flange of the cord spool decreasing in depth toward the periphery and balls provided in the radial ball guide grooves, respectively, and a plurality of interlocking projection means formed on the upper surface of the upper flange of the cord spool and on the upper inner surface of the rotary casing so as to engage when the cord spool is raised away from the bottom plate.
The former known cord type mower is not provided with any suitable control means for regulating the rotation of the cord spool while unwinding the cords by rotating the cord spool. Therefore, the cords can not be unwound regularly and hence, in some cases, the cords are unwound by a length more than necessary, which is dangerous to the operator.
On the other hand, in the latter known cord type mower, the cord spool is restricted from free rotation by a spring, radial ball guide grooves are formed in the flange of the cord spool, and the balls are provided in the radial ball guide grooves, respectively. Therefore, when the empty cord spool is removed from the rotary casing to replenish the cord spool with new cords, it is possible that the springs recoil and fly away and the balls are lost. If such an accident occurs in a grass field, it is troublesome to find the springs and the balls.